1. Field of the Invention
The present invention relates to axle drive assemblies, and more particularly to a three-quarter floating axle drive assembly having a C-ring axle shaft retainer.
2. Description of the Prior Art
Conventionally, axle drive assemblies of motor vehicles include an axle shaft connecting differential side gears to drive wheels. They typically support a weight of the vehicle.
Currently, light motor vehicles, such as cars, light trucks and Sport Utility Vehicles (SUVs), commonly use a semi-floating axle drive assembly that is the most common type of axle drives. In the semi-floating design, the vehicle wheels are attached directly to the axle shafts, and the axle shafts bear the vehicle weight and cornering forces, while transmitting at the same time a torque necessary to propel the vehicle. Typically, a wheel bearing is directly mounted to the axle shaft for rotationally supporting it within an axle tube of an axle housing. Axial loads due to cornering or the like, are reacted along the axle shaft into a differential cross pin. Thus, less expensive types of the wheel bearings can be used as they are not required to carry thrust loads. The semi-floating axle drives are commonly used in applications below approximately 6,000 pound gross axle weight rating. Higher load ratings are difficult to achieve, primarily due to packaging constraints on the size of the wheel bearings.
Heavy-duty trucks typically use full-floating axles, well known in the art. In the full-floating design, the vehicle weight and cornering forces are carried directly into the axle housing through the wheel bearings and an axle spindle. The vehicle wheels are attached to separate hubs that are rotatably supported on the axle spindles. In this design, the axle shafts only have to transmit the torque necessary to propel the motor vehicle. Since the wheel bearings must react the cornering forces, each hub must have two bearings, usually tapered roller bearings spaced a distance apart. These bearings are retained by a nut, which is threaded into the spindle and must be carefully set for end play to ensure proper performance. The full-floating axles are typically used for application exciding approximately 6,000 pound gross axle weight rating, as there is virtually no constraint on the size of the hubs and the wheel bearings.
Three-quarter floating axle design incorporates features of the semi-floating and full-floating axle designs. While it does have separate hubs, there is only a single wheel bearing per hub. The axle shaft is bolted to the hub, and, thereby, stabilizes thereof. A nut retaining the wheel bearing prevents axial displacement of the axle shaft. Thrust loads due to cornering forces are reacted through the wheel bearing. The axle shaft also carries the bending reaction due to cornering forces.
The present invention provides an improved three-quarter floating axle drive assembly.
The axle drive assembly in accordance with the preferred embodiment of the present invention includes an axle housing having an elongated axle tube, a rotatable axle shaft extending through the axle tube, a hub member rotatably supported on the axle tube through an anti-friction bearing assembly and drivingly connected to an outboard end of the axle shaft, and an axle shaft retainer disposed at an inboard end of the axle shaft provided for preventing an outward axial displacement thereof.
In accordance with the preferred embodiment of the present invention, the axle shaft retainer is in the form of a slotted washer, or C-ring, fitted within the recess in the inboard end of the axle shaft. Subsequently, the anti-friction bearing assembly does not carry the thrust loads, thus, eliminating a bearing retaining nut typically present in the three-quarter floating axle drive assemblies of the prior art. Also less expensive types of the wheel bearings may be used.
Preferably, the hub member is integrally formed with a disc brake rotor as a single-piece part, preferably by forging or casting.
The axle drive assembly in accordance with the present invention combines the three-quarter floating axle design with the C-ring axle shaft retainer. It permits higher axle load ratings than the existing semi-floating axle designs, and is simpler and lighter than the existing full-floating and three-quarter floating axle designs.